This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The study is designed to provide long-term safety monitoring for participants in gene transfer studies after the active follow-up phase of each individual study. Frequency of vector marking detection, characterization of clonal proliferation events occurring in gene transfer trials as well as archiving patient samples for further safety tests will be the focus. The study will provide insight into the long-term safety of gene transfer approaches.